Patent Document 1 discloses a tire condition monitoring apparatus installed in a vehicle with wheel assemblies. The tire condition monitoring apparatus of Patent Document 1 includes a receiver and tire condition detecting devices. Each tire condition detecting device is installed in one of the wheel assemblies.
Each tire condition detecting device includes a condition detecting section for detecting the condition of the tire, a transmission circuit, and a transmission antenna. The transmission circuit modulates data of the tire condition detected by the condition detecting section and generates data signals. The transmission antenna transmits the data signals generated by the transmission circuit. The data signals generated by the transmission circuit must be received by the receiver. Therefore, the tire condition detecting device transmits data signals using a protocol compatible with the receiver.